Maneuvering board attachment



Dec. 19, 1950 Q w, MERRIAM, JR 2,534,288

MNEUVERING BOARD ATTACHMENT Filed Oct. 16, 1945 INVENTO CHARLES W.MERRIAM ATTORNEY Patented Dec. 19, 1950 UNITED fES PATENT Dil-"1F Il CIEassszss MANEUVERING BOARD. ATTACHMENT vCharley-W. Merriam, Jr.,"1aunton,Mass.

.Application October .16, 1945, Serial No. .622,664

'3 -Claims. "(CL (S3-76) l((Srranted under the act fof 'March i3, 1883,.as

amended .April 30, 1928; :370 0. .G. 757-) l "This invention :relatestofmaneuvering .and 'more :particularly to `an attachment therefor' rior:facilitating and expediting 'the plotting andlndicating of the-mostdirect course .for intercernlon y,of :a moving target.

.It is :anlobject of the presentinvention to provvide a conventionaltype lof maneuvering lboard .such Vas is used :aboard vaship -withasimple-.and reffective `attachrnent ;by\ means of which the user theboard may easily -and expeditiously der termine the. shortestpossiblecourse for effectingy .the interception ofvavmoving target.

It is another object of they invention', .to provide. an attachment .ofthis character which is 4aliapted to .mounted .on presently .existingmaneuvering boards `with but a `few, simplemodi .ncations .thereto` Withthe above and other objects and .features in view, the invention willnow-bedescribed with reference .to the .accompanying drawings. which:illustrate a :preferred embodimentv of the inven .tion and will bepointed out in theclaims ,In the drawings:

Fig. 1 is a top .plan view .of a maneuvering board with `the attachmentapplied thereto;

Fig; 2 is a. sectional elevation thereof.; and

Fig. 3 is a .diagrammatic view illustrating the `operationfef thedevice.`

The conventional ,maneuvering hoard4 comf prises .a frame Illand, a.disc l2., thev frame being .mounted .on legs 1.3. 'llheframe .and `disc.are preferably made. of transparentplastic material. The frame is`recessed v'as .at L4 to. receive the .disc L2 with its .upper .surface.lying flush with the upper surface of the trama The. discv is markedwith a plurality of concentric circles in ,spaced relation to indicaterange.v The disc is also. marked with a .series of lines extendingradially tromA its. center to its periphery and spaced: -from .eachother .by 10?. At the outer ends of these lines designations .of thenumber of .degrees starting from, -090- .are marked successively aroundthe disc. Corresponding relative bearing designations are; marked on thesurface. of frame Il! around the portion adjacent to the recess I4".

The disc is rotatably mounted vcentrally in the frame'on Ithe peripheryof:v a bushing comprised of upper and lower .sections I6 .and l-B..

respectively.l The lower sectionylf hase flanged receiving .a Spannerwrench to `facilitate the assembling operation. When the parts `areassembled,k=.the recessed portion V23 of the disc 'l2 has justsu'nlcient clearance between the under- :surface of the flanged headofthe section I6, vthe outer surface :of :the shank '25, and the uppersurface of' vthe frame vIl) to permit of its 'free rotary movement intheframe. An upstanding :pin v 29 secured in the flanged head of the section t8. extends into an opening 30 in the frame' l0 to hold thesections IB and Il) stationary.

Vi'lentrallyof the. sectionsV |-6 and i8 is 1a. 'bore "3.2 for receivinga, stud 3'4. The stud 34 'is provided at its .upper end `With a circularflange 3S that is. received within a .recess 33 provided in the-uppersurface of the 'flanged .head of section I5. The depth of the recess .38accommo- .dates ythe flange 3B, so that its upper surface .lies ilushwith the surface lof the disc t2. The lower end of `the .stud M hasthreaded thereon 'an adjusting nut 38 bearing against `an inter- .posedEfriction spring Ml. By adjusting the nut 38 sa vproper degree of"'friction is maintained '-upon the studv and disc 36 vto permit thelatter to be `freely rotatable yand yet held frictionally in vanyposition to which they may be adjusted rela-tiveY to the .disc l2 andfra-me i9. A lock nut 42. bearing against. `the adjusting nut 58 servesto. hold the adjustment secure.

.An LupStanding, yradially extending, support o1' 'arm' V4.3 is formedintegral with the ange 36. The inner- Y'er-1d 4d .of this arm is offsetfrom the :center of the stud a slight distance. Adjacent to the outerend of the arm 43 is a transversely disposed lretaining member or 'lug45 yformedv so vthat the. under-surface lof its 'outwardly projectingportions lie hush with the upper surface ofthe arm proper.

T square 46,3150 preferably made of translparent plastic material, isarranged for mounting on the arm 43. Thel crosshead 48 of this T squareis formed with an external straightedge `5l)y having a measuring scale5l `marked thereon. The leg 52 of the T square is provided with a slot'5i centrally thereof that extends vsubstantially throughout vitsVlength and partially into the crosshead 48. The Width of the slot '54'is substantially the same as the Width of the. arm 43 .so that. the Tsquare .may be .mounted 'thereover withv just suicient clearance toprovide `for sliding movement of ther T square axially of the arm da Thearm serves to guide the A.direction of movement of the T square as lit.vis .slid toward or away from the center 56 civ the. ,maneuvering board.The distance between .the .inner end of slotA .54 and the straightedge50 corresponds exactly with .the distance between the end .41. .ofthe-arm 43 andthe center '56., Hence.v when the inner end of the slotis. brought. tev a position where it abuts against .the

end 44, the straightedge 50 intersects exactly the center 56 of theboard.

Adjacent to the outer end of the slot 54 there are provided a pair ofoppositely disposed en'' largements 58, the contours of which,correspond to the conguration of the outwardly projecting portions ofthe lug 45. Therefore, to mount the T square upon the maneuvering board,it is only necessary to align the enlarged portions 58 with lug 45whereupon the T square will drop over the arm 43 and lie with itsundersurface in sliding contact with the upper surface `of the disc I2.Now, upon sliding the T square to a position where the enlarged portions58 are out of alignment with the lug-45, the undersurf ace of theoutwardly projecting portions of the latter will lightly engage theupper surfaces of the leg 52 of the T square at 'the portions thereoflying adjacent to the opposite sides of the'slot l54. The upper surfaceof the leg 52 of the T square has marked thereon, adjacent to the slot54, a measuring scale 4l from which can be determined the distancebetween the straightedge 50 and the center 56 for a purpose which willhereinafter appear.

Referring to Fig..3, wherein is shown a typical lillustration'of the useof the maneuvering board with the attachment thereon, the spot Arepresents the initial nx which'has been taken on lan enemy plane, byradar or other means, and

plotted upon the board as to range and bearing. A second fix B, of theenemy plane is similarly plotted upon the board. A third x C, on afriendly plane, is similarly taken and plotted upon the board. Thestraightedge50 of the T square 46 is placed on fixes A and B and theline of night so established, is projected as a line upon the board.Straightedge 50 `is then positioned on points B and C andtheI midpoint Dis established and marked upon' the board by the use of the measuringscale 5l. The T square 52 is then positioned so that one of the lines ofthe measuring scale 5| of the straightedge 50 is placed parallel to theline BC and, at the same time, the straightedge passes through point D.This permits the erection of a line perpendicular to BC at mid-point D.s This perpendicular will cross line AB extended, at E. Line EC is thenthe hypotenuse of a triangle CDE and is equal to the hypotenuse EB ofthe triangle EDB.V Then with the straightedge 50 on EC the T squareisrmoved axially of the arm 43 to a position wherethe straightedge 5!passes through the center 56 of the maneuvering board. The line 561 isparallel to line CE, and is, therefore, the course to be taken by thefriendly plane starting from point C.

A basically similar geometric construction can be made for a friendlyplane starting from a point over the center point 56, said constructionemploying the use of the meausring scale 41 and the slot 54.

It will be understood that the foregoingas` sumes that the friendlyplane is capable of traveling. at a speed equal to the enemy plane and,moreover, it is manifestly necessary that the angle EBC be suicientlyless thanv9 0 to permit the course to be followed by the friendly planefrom -point C, to be such as to intersect the AB extended, within theconfines of the maneuvering board.

The vinvention described herein may be manuthe United States of- Americafor government 4 purposes without the payment of any royalty .thereon ortherefor.

Having described the invention what is claimed as novel and desired tobe protected by Letters Patent of the United States is:

1. An attachment for a maneuvering board comprising, a T square formedof uniformly fiat transparent material having an elongated slotlengthwise of its leg and being formed with a straightedge on itscrosshead, said slot having a pair of oppostely disposed enlargementstherein, a stud adapted to be rotatably mounted centrally of saidmaneuvering board, an arm extending radially of said board andhorizontally disposed on said stud, said arm being of a width that isjust sufiicient to t with sliding 'clearance within said slot, atransversely extending lug on said arm in nonrotatable 'relationtherewith of a size and shape to receive the enlarged portion of saidslot, whereby the square may be mounted on said arm by aligning theenlarged portion of 'said slot with said lug and whereby the square maythereafter be removably retained on said arm by sliding the square sothat said lug engages the upper surfaces of those portions of the squarelying adjacent to the opposite sides of said slot.

2. A maneuvering board comprising, in combination, a frame, a disccentrally4v supported within saidv frame, said frame and disc beingmarked with correlated range and bearing designations, a hollow bushingcentrally secured to`said frame and extending through and 10- tatablysecuring said disc to .said frame, a stud rotatably disposed wthinsaidbushing, frictional means forrestraining rotation of said stud relativeto said frame, an elongated arm on-said stud extending radiallytherefrom in spaced relation from the center of said stud and disposedover and in contacting relation with said disc, a T square formed ofuniformly fiat transparent material and including a leg and a crosshead,said crosshead being formed withl a straight edge, said leg being formedwith a lengthwise slot and tted on said arm in nonr'otatab'lerelationship therewith, said arm being in slidable relation with thewalls of said slot, said T square being supported onsaid arm incontacting and slidable relation with said disc and said frame.

3. Apparatus as in claim 2 and including means on said arm for arrestingthe T squarel against further movement when said straightedge has beenbrought to a position where it intersects the center of said disc.

CHARLES W. MERRIAM, Je.

REFERENCES CITED The following references `are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 252,065 Thomas Jan. 10, 1882499,495," 1 Baker June 13, 1893 '726,973 McKinnon May 5; 1903 51,133,540Dannenberg Mar. 30, 1915 1,296,704 Sayre Mar. 11, 1919 1,853,740 MuellerApr. 12, 1932 1,917,273 Weems July 11, 1933 FOREIGN PATENTS NumberCountry Date 9,145 Great Britain 1907 22,117 I Great Britain 1913

